Mr Abdul Salam said the aircraft had targeted the region of Jabal al-Dukhan, the villages of Hassama and Shida, and the town of al-Malahit, which lies 7km (4 miles) inside Yemen, killing civilians.

He also denied that rebel fighters had crossed the Saudi border, saying those who had been detained were illegal migrants, and accused the Saudi government of allowing the Yemeni military to use its territory to launch attacks.

But Saudi Assistant Defence Minister Khaled Bin Sultan insisted on Sunday that Saudi troops were merely seeking to force the rebels from its territory and seal the border to prevent incursions.

Saudi television aired footage on Sunday of Saudi soldiers capturing and blindfolding men who were identified as Houthi fighters.

On Saturday, Yemeni President Ali Abdullah Saleh vowed to crush the rebels, and that there would be no let up in the battle "until we bring this tyrannical, traitorous and mercenary group to an end".

"The war just started two days ago, and what has been happening in the past six years was just... training for the army," he said. "The war will never stop no matter how much money or martyrs it costs."

'Discrimination'

The Houthis, named after the family of their leader, say they want greater autonomy and a greater role for their version of Shia Islam. They complain that their community is discriminated against.

They also accuse Saudi Arabia of supporting the Yemeni armed forces by allowing them to launch attacks from its territory, a charge which both countries deny.

Saudi Arabia says it has captured several Houthi fighters on its territory

The Yemeni government accuses the rebels of wanting to re-establish Zaydi Shia clerical rule, and of receiving support from Iran.

The Zaydi Shia community are a minority in Yemen, but make up the majority in the north of the country.

The insurgents first took up arms against the government in 2004, after which government forces killed or captured much of the Houthi leadership.

The government launched a fresh offensive in August 2009 which has precipitated a new wave of intense fighting.